Antimicrobial resistance in Europe and its potential impact on empirical therapy

Effect of precursors on carbon dot functionalization and applications: a review

Carbon dots (CDs) are a type of carbon-based nanoparticle (NP) that have risen in popularity due to their unique tuneable physicochemical and optical properties. CDs have received a significant amount of attention in biological based applications due to their low cytotoxicity, stable photoluminescence, and small size. They have demonstrated the ability to retain certain properties from their carbon precursors, enabling NP design via precursor selection. Thus, direct functionalization of a CD can be achieved without the need for post synthesis modification. However, CDs derived from the same class of carbon precursor can also have profoundly variable applications. Indicating that, in conjunction with precursor properties, other functional attributes can be imposed on the CD during the synthesis process to enable cross-cutting applications from a single carbon precursor. Here, we will highlight various CD precursors and the resulting multifunctional CDs, as well as rational design of CDs for specific biological and materials science applications via precursor selection.

Biocompatible Zn-Phthalocyanine/Gelatin Nanofiber Membrane for Antibacterial Therapy

In this study, the fabrication and characterization of Zn-phthalocyanine/gelatin nanofibrous membranes is reported using the electrospinning technique. The membranes exhibit a homogeneous distribution of Zn-phthalocyanine within the gelatin matrix, maintaining the structural integrity and photosensitizing properties of the phthalocyanine. Scanning electron microscopy revealed that the electrospun fibers possess diameters ranging results as 100-300, 200-700, and 300-800 nm for Gel, ZnPc/Gel 1, and ZnPc/Gel 2, respectively. The addition of ZnPc does not decrease the hydrophilicity of the Gel membrane. The nanofibrous membranes showed good cytocompatibility, as indicated by the high viability of Vero cells exposed to membrane extracts. Furthermore, these composites supported cell adhesion and proliferation on their surfaces. The two Zn-phthalocyanine/gelatin nanofiber formulations exhibited significant antimicrobial activity toward Escherichia Coli (E. Coli) and Staphylococcus Aureus (S. Aureus) under visible light illumination, achieving reductions of 3.4 log10 and 3.6 log10 CFU mL-1 for E. coli, and 3.9 log10 and 4.1 log10 CFU mL-1 for S. aureus. These results demonstrate the potential of Zn-phthalocyanine/gelatin nanofibrous membranes as effective agents in antibacterial photodynamic therapy, providing a promising solution to control bacterial infections and antibiotic resistance.

A game of resistance: War between bacteria and phages and how phage cocktails can be the solution

While phages hold promise as an antibiotic alternative, they encounter significant challenges in combating bacterial infections, primarily due to the emergence of phage-resistant bacteria. Bacterial defence mechanisms like superinfection exclusion, CRISPR, and restriction-modification systems can hinder phage effectiveness. Innovative strategies, such as combining different phages into cocktails, have been explored to address these challenges. This review delves into these defence mechanisms and their impact at each stage of the infection cycle, their challenges, and the strategies phages have developed to counteract them. Additionally, we examine the role of phage cocktails in the evolving landscape of antibacterial treatments and discuss recent studies that highlight the effectiveness of diverse phage cocktails in targeting essential bacterial receptors and combating resistant strains.

Establishment of a risk prediction model for multidrug-resistant bacteria in deceased organ donors: a retrospective cohort study in China

Background

Multidrug resistance in bacteria is a serious problem in organ transplantations. This study aimed to identify risk factors and establish a predictive model for screening deceased organ donors for multidrug-resistant (MDR) bacteria.

Methods

A retrospective cohort study was conducted at the First Affiliated Hospital of Zhejiang University School of Medicine from July 1, 2019 to December 31, 2022. The univariate and multivariate logistic regression analysis was used to determine independent risk factors associated with MDR bacteria in organ donors. A nomogram was established based on these risk factors. A calibration plot, receiver operating characteristic (ROC) curve, and decision curve analysis (DCA) were used to estimated the model.

Results

In 164 organ donors, the incidence of MDR bacteria in culture was 29.9%. The duration of antibiotic use ≥3 days (odds ratio [OR] 3.78, 95% confidence interval [CI] 1.62-8.81, p=0.002), length of intensive care unit (ICU) stay per day(OR 1.06, 95% CI 1.02-1.11, p=0.005) and neurosurgery (OR 3.31, 95% CI 1.44-7.58, p=0.005) were significant independent predictive factors for MDR bacteria. The nomogram constructed using these three predictors displayed good predictive ability, with an area under the ROC curve value of 0.79. The calibration curve showed a high consistency between the probabilities and observed values. DCA also revealed the potential clinical usefulness of this nomogram.

Conclusions

The duration of antibiotic use ≥3 days, length of ICU stay and neurosurgery are independent risk factors for MDR bacteria in organ donors. The nomogram can be used to monitor MDR bacteria acquisition risk in organ donors.

The Optimal Effective Concentration Combination (OPECC) as a Novel Method for Evaluating the Effects of Binary Application of Antibacterial Compounds

Combination therapies appear to be beneficial for preventing bacterial resistance to antibacterial approaches. The aim of this study was to define and determine an optimal effective concentration combination (OPECC) for binary application of antibacterial compounds. The antiseptics chlorhexidine (CHX), benzalkonium chloride (BAC), and cetylpyridinium chloride (CPC), as well as the antibiotic ciprofloxacin (CIP), were tested against planktonic Escherichia coli in binary combinations by applying a checkerboard assay, and then evaluated according to the established synergism principles. Extending the checkerboard method, the optical density (OD) of the wells was measured photometrically. On the borderline between effective (OD = 0) and non-effective (OD > 0) eradication of the bacterial cultures, the OPECC was determined. Binary combinations of CPC or CHX with BAC were assessed as either synergistic or indifferent, respectively, while there was no OPECC to calculate. For all other binary combinations, an OPECC was derivable, and these were assessed as either synergistic or indifferent. In conclusion, the evaluation of the binary combination application of antibacterial compounds based on the checkerboard method was refined to such an extent that it was possible to determine at least one concentration pair that could be defined and considered as an OPECC, independently of the evaluation of the system according to the different synergy principles. In general, the method presented herein for determining an OPECC can be applied to any conceivable method or system aimed at the eradication of a pathogen.

Photodynamic Therapy: A Prospective Therapeutic Approach for Viral Infections and Induced Neoplasia

The recent COVID-19 pandemic outbreak and arising complications during treatments have highlighted and demonstrated again the evolving ability of microorganisms, especially viral resistance to treatment as they develop into new and strong strains. The search for novel and effective treatments to counter the effects of ever-changing viruses is undergoing. Although it is an approved procedure for treating cancer, photodynamic therapy (PDT) was first used against bacteria and has now shown potential against viruses and certain induced diseases. PDT is a multi-stage process and uses photosensitizing molecules (PSs) that accumulate in diseased tissues and eradicates them after being light-activated in the presence of oxygen. In this review, studies describing viruses and their roles in disrupting cell regulation mechanisms and signaling pathways and facilitating tumorigenesis were described. With the development of innovative “or smart” PSs through the use of nanoparticles and two-photon excitation, among other strategies, PDT can boost immune responses, inactivate viral infections, and eradicate neoplastic cells. Visualization and monitoring of biological processes can be achieved in real-time with nanomedicines and better tissue penetration strategies. After photodynamic inactivation of viruses, signaling pathways seem to be restored but the underlying mechanisms are still to be elucidated. Light-mediated treatments are suitable to manage both oncogenic viral infections and induced neoplasia.

Molecular Mechanisms of Drug Resistance in Staphylococcus aureus

This paper discusses the mechanisms of S. aureus drug resistance including: (1) introduction. (2) resistance to beta-lactam antibiotics, with particular emphasis on the mec genes found in the Staphylococcaceae family, the structure and occurrence of SCCmec cassettes, as well as differences in the presence of some virulence genes and its expression in major epidemiological types and clones of HA-MRSA, CA-MRSA, and LA-MRSA strains. Other mechanisms of resistance to beta-lactam antibiotics will also be discussed, such as mutations in the gdpP gene, BORSA or MODSA phenotypes, as well as resistance to ceftobiprole and ceftaroline. (3) Resistance to glycopeptides (VRSA, VISA, hVISA strains, vancomycin tolerance). (4) Resistance to oxazolidinones (mutational and enzymatic resistance to linezolid). (5) Resistance to MLS-B (macrolides, lincosamides, ketolides, and streptogramin B). (6) Aminoglycosides and spectinomicin, including resistance genes, their regulation and localization (plasmids, transposons, class I integrons, SCCmec), and types and spectrum of enzymes that inactivate aminoglycosides. (7). Fluoroquinolones (8) Tetracyclines, including the mechanisms of active protection of the drug target site and active efflux of the drug from the bacterial cell. (9) Mupirocin. (10) Fusidic acid. (11) Daptomycin. (12) Resistance to other antibiotics and chemioterapeutics (e.g., streptogramins A, quinupristin/dalfopristin, chloramphenicol, rifampicin, fosfomycin, trimethoprim) (13) Molecular epidemiology of MRSA.

Evolutionary Dynamics between Phages and Bacteria as a Possible Approach for Designing Effective Phage Therapies against Antibiotic-Resistant Bacteria

With the increasing global threat of antibiotic resistance, there is an urgent need to develop new effective therapies to tackle antibiotic-resistant bacterial infections. Bacteriophage therapy is considered as a possible alternative over antibiotics to treat antibiotic-resistant bacteria. However, bacteria can evolve resistance towards bacteriophages through antiphage defense mechanisms, which is a major limitation of phage therapy. The antiphage mechanisms target the phage life cycle, including adsorption, the injection of DNA, synthesis, the assembly of phage particles, and the release of progeny virions. The non-specific bacterial defense mechanisms include adsorption inhibition, superinfection exclusion, restriction-modification, and abortive infection systems. The antiphage defense mechanism includes a clustered regularly interspaced short palindromic repeats (CRISPR)–CRISPR-associated (Cas) system. At the same time, phages can execute a counterstrategy against antiphage defense mechanisms. However, the antibiotic susceptibility and antibiotic resistance in bacteriophage-resistant bacteria still remain unclear in terms of evolutionary trade-offs and trade-ups between phages and bacteria. Since phage resistance has been a major barrier in phage therapy, the trade-offs can be a possible approach to design effective bacteriophage-mediated intervention strategies. Specifically, the trade-offs between phage resistance and antibiotic resistance can be used as therapeutic models for promoting antibiotic susceptibility and reducing virulence traits, known as bacteriophage steering or evolutionary medicine. Therefore, this review highlights the synergistic application of bacteriophages and antibiotics in association with the pleiotropic trade-offs of bacteriophage resistance.

Impact of Guideline Adherence on Outcomes in Patients Hospitalized with Community-Acquired Pneumonia (CAP) in Hungary: A Retrospective Observational Study

Community-acquired pneumonia (CAP) is a leading cause of morbidity and mortality worldwide. This retrospective observational study evaluated the antibiotic prescription patterns and associations between guideline adherence and outcomes in patients hospitalized with CAP in Hungary. Main outcome measures were adherence to national and international CAP guidelines (agent choice, dose) when using empirical antibiotics, antibiotic exposure, and clinical outcomes. Demographic and clinical characteristics of patients with CAP in the 30-day mortality and 30-day survival groups were compared. Fisher’s exact test and t-test were applied to compare categorical and continuous variables, respectively. Adherence to the national CAP guideline for initial empirical therapies was 30.61% (45/147) for agent choice and 88.89% (40/45) for dose. Average duration of antibiotic therapy for CAP was 7.13 ± 4.37 (mean ± SD) days, while average antibiotic consumption was 11.41 ± 8.59 DDD/patient (range 1−44.5). Adherence to national guideline led to a slightly lower 30-day mortality rate than guideline non-adherence (15.56% vs. 16.67%, p > 0.05). In patients aged ≥ 85 years, 30-day mortality was 3 times higher than in those aged 65−84 years (30.43% vs. 11.11%). A significant difference was found between 30-day non-survivors and 30-day survivors regarding the average CRP values on admission (177.28 ± 118.94 vs. 112.88 ± 93.47 mg/L, respectively, p = 0.006) and CCI score (5.71 ± 1.85 and 4.67 ± 1.83, p = 0.012). We found poor adherence to the national and international CAP guidelines in terms of agent choice. In addition, high CRP values on admission were markedly associated with higher mortality in CAP.

Membrane damage as mechanism of photodynamic inactivation using Methylene blue and TMPyP in Escherichia coli and Staphylococcus aureus

The worldwide threat of antibiotic resistance requires alternative strategies to fight bacterial infections. A promising approach to support conventional antibiotic therapy is the antimicrobial photodynamic inactivation (aPDI). The aim of this work was to show further insights into the antimicrobial photodynamic principle using two photosensitizers (PS) of different chemical classes, Methylene Blue (MB) and TMPyP, and the organisms Escherichia coli and Staphylococcus aureus as Gram-negative and Gram-positive representatives. Planktonic cultures of both species were cultured under aerobic conditions for 24 h followed by treatment with MB or TMPyP at various concentrations for an incubation period of 10 min and subsequent irradiation for 10 min. Ability to replicate was evaluated by CFU assay. Accumulation of PS was measured using a spectrophotometer. The cytoplasmic membrane integrity was investigated by flow cytometry using SYBR Green and propidium iodide. In experiments on the replication ability of bacteria after photodynamic treatment with TMPyP or MB, a killing rate of 5 log₁₀ steps of the bacteria was achieved. Concentration-dependent accumulation of both PS was shown by spectrophotometric measurements whereby a higher accumulation of TMPyP and less accumulation of MB was found for S. aureus as compared to E. coli. For the first time, a membrane-damaging effect of TMPyP and MB in both bacterial strains could be shown using flow cytometry analyses. Furthermore, we found that reduction of the replication ability occurs with lower concentrations than needed for membrane damage upon MB suggesting that membrane damage is not the only mechanism of aPDI using MB.

Resistance Trend Estimation Using Regression Analysis to Enhance Antimicrobial Surveillance: A Multi-Centre Study in London 2009-2016

In the last years, there has been an increase of antimicrobial resistance rates around the world with the misuse and overuse of antimicrobials as one of the main leading drivers. In response to this threat, a variety of initiatives have arisen to promote the efficient use of antimicrobials. These initiatives rely on antimicrobial surveillance systems to promote appropriate prescription practices and are provided by national or global health care institutions with limited consideration of the variations within hospitals. As a consequence, physicians' adherence to these generic guidelines is still limited. To fill this gap, this work presents an automated approach to performing local antimicrobial surveillance from microbiology data. Moreover, in addition to the commonly reported resistance rates, this work estimates secular resistance trends through regression analysis to provide a single value that effectively communicates the resistance trend to a wider audience. The methods considered for trend estimation were ordinary least squares regression, weighted least squares regression with weights inversely proportional to the number of microbiology records available and autoregressive integrated moving average. Among these, weighted least squares regression was found to be the most robust against changes in the granularity of the time series and presented the best performance. To validate the results, three case studies have been thoroughly compared with the existing literature: (i) Escherichia coli in urine cultures; (ii) Escherichia coli in blood cultures; and (iii) Staphylococcus aureus in wound cultures. The benefits of providing local rather than general antimicrobial surveillance data of a higher quality is two fold. Firstly, it has the potential to stimulate engagement among physicians to strengthen their knowledge and awareness on antimicrobial resistance which might encourage prescribers to change their prescription habits more willingly. Moreover, it provides fundamental knowledge to the wide range of stakeholders to revise and potentially tailor existing guidelines to the specific needs of each hospital.

Carriage Prevalence of Extended-Spectrum β-Lactamase Producing Enterobacterales in Outpatients Attending Community Health Centers in Blantyre, Malawi

Antimicrobial resistance due to extended-spectrum β-lactamase (ESBL) production by Enterobacterales is a global health problem contributing to increased morbidity and mortality, particularly in resource-constrained countries. We aimed to determine the prevalence of extended-spectrum β-lactamase-producing Enterobacterales (ESBL-E) in community patients in Blantyre, Malawi. Clinical samples were collected from 300 patients and screened for ESBL-E using a CHROMagar^TM ESBL medium. Confirmation of ESBL production was done by a combination disk test (CDT). The prevalence of community-acquired ESBL-E was 16.67% (50/300, 95% CI = 12.43–20.91%). The most common ESBL-E species isolated was Escherichia coli (66%). All ESBL-E isolates were resistant to Trimethoprim-Sulfamethoxazole except for 2% of E. coli. Besides this, all ESBL-E were susceptible to Imipenem and only 4% were resistant to Meropenem. No patients with a positive ESBL-E phenotype had a history of hospital admission in the last three months, and the carriage of ESBL-E was neither associated with the demographic nor the clinical characteristics of participants. Our findings reveal a low presence of ESBL-E phenotypes in community patients. The low prevalence of ESBL-E in the community settings of Blantyre can be maintained if strong infection and antimicrobial use-control strategies are implemented.

Lower Respiratory Tract Pathogens and Their Antimicrobial Susceptibility Pattern: A 5-Year Study

Lower respiratory tract infections (LRTIs) are the most common infections in humans. It is estimated that 2.74 million deaths worldwide occur each year due to LRTIs. The aim of the study was to determine the frequency and antibiotic susceptibility pattern of microorganisms isolated from respiratory samples of patients with LRTIs. Between January 2015 and December 2019, a total of 7038 sputum and bronchoaspirate samples from suspected LRTI patients were collected. Among them, 2753 samples (39.1%) showed significant microbial growth on culture media. The LRTI rate was higher in patients with male gender (67.1%) and with age between 40–59 years (48.6%). The microorganism identification and antibiotic susceptibility testing were performed with Vitek 2. Out of 4278 isolates species, 3102 (72.5%) were Gram-negative bacteria, 1048 (24.5%) were Gram-positive bacteria, and 128 (3.0%) were Candida spp. Major microorganisms isolated were Acinetobacter baumannii (18.6%), Staphylococcus aureus (15.2%), Pseudomonas aeruginosa (14.2%), and Klebsiella pneumoniae (10.9%). In antimicrobial susceptibility testing, Staphylococcus aureus isolates were mostly resistant to Penicillin G (84.1%) and Oxacillin (48.1%), whereas they demonstrated maximum sensitivity to Tigecycline (100%) and Linezolid (99.5%). Among Gram-negative isolates, Acinetobacter baumannii showed maximum sensitivity to Colistin but was resistant to other antibiotics (95–99%). Klebsiella pneumoniae isolates were mostly resistant to Cefotaxime (72.7%) and sensitive to Gentamicin (54.3%), and Pseudomonas aeruginosa was resistant to Ciprofloxacin (40.3%) and sensitive to Amikacin (85.9%). Gram-negative bacteria represented the species most commonly isolated. A high rate of antimicrobial resistance was observed in this study. In conclusion, the correct identification of causative microorganisms and their susceptibility patterns to antibiotics is crucial for choosing targeted and effective antibiotic therapy in LRTIs, and to prevent the emergence of multidrug-resistant bacteria.

Antimicrobial Susceptibility Trends of Streptococcus pneumoniae by Age Groups Over Recent 10 Years in a Single Hospital in South Korea

PURPOSE

Streptococcus pneumoniae (S. pneumoniae) causes respiratory tract infections. Its non-vaccine serotypes and multidrug-resistant pneumococcal diseases have increased during the post-pneumococcal vaccination era. Therefore, it is important to understand the regional and age-related antimicrobial susceptibility of S. pneumoniae to select appropriate empirical antimicrobials.

MATERIALS AND METHODS

We retrospectively studied trends in the antimicrobial resistance of S. pneumoniae to commonly prescribed antibiotics in patient groups of various ages at a single teaching hospital in Jeju Island from 2009 to 2018.

RESULTS

In total, 1460 S. pneumoniae isolates were obtained during the study period. The overall antimicrobial resistance rates of S. pneumoniae to penicillin, erythromycin, ceftriaxone, levofloxacin, and vancomycin were 16.2%, 84.7%, 25.9%, 3.3%, and 0.0%, respectively, and the MDR rate was 6.7%. Erythromycin and ceftriaxone resistance rates increased by years; however, they were significantly reduced in adult groups. Levofloxacin resistance and MDR rates were also higher in adult groups. Overall, the MDR rate significantly increased during the recent 10 years, as well as in patients with a history of hospitalization within 90 days [odds ratio (OR)=3.58, 95% confidence interval (CI)=1.91-6.71] and sinusitis (OR=4.98, 95% CI=2.07-11.96).

CONCLUSION

Erythromycin and ceftriaxone resistance rates and the MDR rate of S. pneumoniae significantly increased during the recent 10 years; the trends in individual antimicrobial resistance rates significantly differed between the age groups. This study indicates the need for caution when using ceftriaxone as an empirical antimicrobial against pneumococcal infections.

Diversity of β-lactamase-encoding genes in wastewater: bacteriophages as reporters

A reservoir of antibiotic resistance genes (ARGs) is present in pathogenic, commensal, and environmental bacteria as well as in mobile genetic elements, including bacteriophages. Wastewater treatment plants (WWTPs) are considered hotspots for the spread of ARGs. The aim of this work was to analyze the diversity of the highly prevalent ARGs bla_CTX-M and bla_TEM in bacterial and bacteriophage fractions associated with human and animal environments through the study of urban waste and animal residues discharged into WWTPs to provide information about the composition and maintenance of the current resistome in Buenos Aires, Argentina. The results showed that a putative extended-spectrum variant of the bla_TEM gene was the most frequently detected, with bla_TEM-116 being the most prevalent, while a recently described type, bla_TEM-229, was also found. In the bacteriophage fraction, we detected bla_CTX-M genes from four out of the five clusters described. The detection of bla_{CTX- M-9}-like and bla_CTX-M-25-like genes was unexpected based on surveys of the ARGs from clinical pathogens circulating regionally. The finding of divergent bla_CTX-M sequences associated with previously reported environmental genes argues in favor of the natural environment as a reservoir of resistance genes. ARGs were detected in bacteriophages as frequently as in bacterial communities, and furthermore, the bla_CTX-M genes were more diverse in the bacteriophage fraction. Bacteriophages might therefore play a role in the spread of ARGs in the environment, but they might also be used as "reporters" for monitoring circulating ARGs.

Evaluation of antimicrobial photodynamic activities of 5-aminolevulinic acid derivatives

BACKGROUND

Antibiotic resistance is increasing day by day, thereby increase the chances of more infections by resistant bacteria. In this situation, antimicrobial photodynamic therapy (aPDT) is gaining more attraction.

OBJECTIVE

To evaluate the antimicrobial effect of ALA derivatives using photodynamic therapy.

MATERIALS AND METHODS

In this study, we evaluated the aPDT effect of different derivatives of 5-ALA. In vivo and in vitro studies were performed to measure the antimicrobial activity. Different light doses and different concentrations of drugs were used to test anti-bacterial effect of drugs as well as to detect any physiological changes in animal model after the treatment.

RESULTS

In vivo studies revealed that ALA-methyl ester, ALA-hexyl ester, and ALA-13A are potent photosensitizers. In vitro studies involved wound healing rate, body weight, and dietary intake were evaluated, and results showed that ALA, ALA-methyl ester, ALA-hexyl ester, and ALA-13A had good anti-bacterial effects, fast healing rate, and no effect on other physical parameters.

CONCLUSION

Photodynamic therapy is increasingly used to treat different types of skin infections caused by bacterial strains. Our studies revealed that ALA-methyl ester, ALA-hexyl ester, and ALA-13A are promising photosensitizers for photodynamic therapy to inhibit the growth of resistant bacterial strains.

Insights Into Mechanisms of Antimicrobial Photodynamic Action Toward Biofilms Using Phenalen-1-One Derivatives as Photosensitizers

Introduction

In view of increasing resistance against antibiotics and antiseptics, antimicrobial photodynamic therapy (aPDT) may be a promising approach for use in dentistry. The aim of this study was to investigate the mechanism of action of aPDT with the phenalene-1-one derivatives SAPYR and SA-PN-05 as photosensitizers by evaluating bacterial ability to replicate, membrane integrity, metabolic activity, and formation of reactive oxygen species (ROS) in biofilms of Actinomyces naeslundii, Streptococcus mutans, and Escherichia coli.

Materials and Methods

Single-species biofilms (A. naeslundii, S. mutans, and E. coli) were cultured under aerobic conditions for 48 h followed by treatment with the photosensitizers SAPYR and SA-PN-05 at various concentrations (0, 50, 100, 500 μM) and different incubation periods of 5, 10, 20, and 30 min and subsequent irradiation for 10 min (Waldmann PIB 3000; λ_em = 360–600 nm; 50 mW/cm²; 30 J/cm²). Control samples were treated with dH₂O and kept in dark for the same periods. Bacterial ability to replicate was evaluated by colony forming unit (CFU) assay. The cytoplasmic membrane integrity was investigated by flow cytometry using SYBR Green and propidium iodide and visualized by scanning and transmission electron microscopy. For SAPYR, metabolic activity and formation of intracellular ROS after irradiation were evaluated via luminescence and fluorometric assays, respectively.

Results

SAPYR showed antimicrobial effects (>3 log₁₀ CFU reduction) on S. mutans after 5 min and on A. naeslundii after 20 min incubation and light activation. For E. coli, CFU reduction was >2 log₁₀ after 30 min of incubation. SA-PN-05 showed an antimicrobial effect after 5 min for all bacteria. Membrane damage upon aPDT with SAPYR was observed for E. coli, but not for S. mutans and A. naeslundii. Following treatment with SA-PN-05, irradiated samples and dark controls of all three species showed loss of membrane integrity. Luminescence and fluorometric assays showed a reduction in metabolic activity and an increase in formation of intracellular ROS in all three species upon aPDT treatment with SAPYR.

Conclusion

The observed loss in ability to replicate upon aPDT with SAPYR in single-species biofilms may be due to an increase in formation of intracellular ROS upon photodynamic treatment.

Ampicillin-mediated functionalized gold nanoparticles against ampicillin-resistant bacteria: strategy, preparation and interaction studies

Antibiotic resistance is a highly challenging concern of infectious diseases, and it requires a rational approach to overcome. Through this work, we have synthesized ampicillin-capped gold nanoparticles (Amp-Au NPs) and studied its interaction with bacterial cells. In this process of synthesis, the primary amine group of ampicillin acts as both reducing as well as capping agent. In addition to synthesized gold nanoparticles, the β-lactam ring remains free to interact with bacteria. This approach not only utilizes the maximum efficiency of nanoparticles and antibiotics towards ampicillin sensitive bacterial cells but also proves to be effective against ampicillin resistance bacteria. Our results illustrate that the optimized system of Amp-Au NPs was formulated by taking 1.25 mM ampicillin and 10^-2 of gold ions concentration. UV-vis spectrum of gold nanoparticles and the presence of ampicillin were recorded at around 540 nm and 259 nm, respectively. Microscopic images indicate that particles are nearly spherical and are in size range between 25 and 50 nm. Moreover, formulated Amp-Au NPs show successful accumulation onto the surface of the bacterial cell as a result of which pores were formed into the bacterial membrane. The entry of nanoparticles into bacterial cells was validated through both atomic force microscopy and fluorescent microscopy. The adhesive properties of this coating material and its stability in various pH, i.e. pH 3, pH 7 and pH 10 conditions, could make them a good candidate in the prevention of biofilm formation. Amp-Au NPs show promising antimicrobial activity against ampicillin resistance Escherichia coli bacteria. Furthermore, antimicrobial studies indicate that the efficacy of Amp-Au NPs increased against both ampicillin sensitive and ampicillin resistance bacteria up to sixteen folds and four folds respectively.

Carbon Dots as Potent Antimicrobial Agents

Carbon dots (CDots) have emerged to represent a highly promising new platform for visible/natural light-activated microbicidal agents. In this article, the syntheses, structures, and properties of CDots are highlighted, representative studies on their activities against bacteria, fungi, and viruses reviewed, and the related mechanistic insights discussed. Also highlighted and discussed are the excellent opportunities for potentially extremely broad applications of this new platform, including theranostics uses.

Bloodstream infections caused by carbapenem-resistant Acinetobacter baumannii: Clinical features, therapy and outcome from a multicenter study

OBJECTIVES

bloodstream infections (BSI) due to multidrug-resistant (MDR) Acinetobacter baumannii (AB) have been increasingly observed among hospitalized patients.

METHODS

prospective, observational study conducted among 12 large tertiary-care hospitals, across 7 Italian regions. From June 2017 to June 2018 all consecutive hospitalized patients with bacteremia due to MDR-AB were included and analyzed in the study.

RESULTS

During the study period 281 episodes of BSI due to MDR-AB were observed: 98 (34.8%) episodes were classified as primary bacteremias, and 183 (65.2%) as secondary bacteremias; 177 (62.9%) of them were associated with septic shock. Overall, 14-day mortality was observed in 172 (61.2%) patients, while 30-day mortality in 207 (73.6%) patients. On multivariate analysis, previous surgery, continuous renal replacement therapy, inadequate source control of infection, and pneumonia were independently associated with higher risk of septic shock. Instead, septic shock and Charlson Comorbidity Index >3 were associated with 14-day mortality, while adequate source control of infection and combination therapy with survival. Finally, septic shock, previous surgery, and aminoglycoside-containing regimen were associated with 30-day mortality, while colistin-containing regimen with survival.

CONCLUSIONS

BSI caused by MDR-AB represents a difficult challenge for physicians, considering the high rates of septic shock and mortality associated with this infection.

Phenotypic and Genotypic Characterization of ESBL-, AmpC-, and Carbapenemase-Producing Klebsiella pneumoniae and Escherichia coli Isolates

OBJECTIVES

Drug resistance among gram-negative bacteria is a worldwide challenge. Due to the importance of drug-resistant Klebsiella pneumoniae and Escherichia coli strains in hospital-acquired infections, we aimed to determine the phenotypic and genotypic characteristics of ESBL-, AmpC-, and carbapenemase-producing isolates obtained from hospitalized patients in Tehran and Ilam (Iran).

MATERIALS AND METHODS

In total, 90 K. pneumoniae isolates and 65 E. coli isolates were collected from various infections. Phenotypic identification of bacterial isolates was performed using standard methods. Phenotypic screening of ESBL, AmpC, and carbapenemase enzymes was carried out. Detection of ESBL, AmpC, and carbapenemase genes was also performed by the PCR method.

RESULTS

Phenotypic detection tests showed that 36 (40%) K. pneumoniae and 23 (35.4%) E. coli isolates were ESBL producers. Moreover, 18 (20%) and 6 (9.2%) K. pneumoniae and E. coli isolates were AmpC producers, respectively. Modified Hodge test results indicated that 39 (43.3%) K. pneumoniae and 18 (27.7%) E. coli isolates produced carbapenemase. Molecular tests showed that 40% of K. pneumoniae and 36.9% of E. coli isolates were ESBL positive. AmpC was detected in 24.4 and 13.8% of K. pneumoniae and E. coli isolates. Carbapenemase was detected in 34 (37.8%) K. pneumoniae and 13 (20%) E. coli isolates. -Conclusion: In this study, 3 K. pneumoniae isolates simultaneously carried ESBL, AmpC, and carbapenemase genes. Up-to-date strategies such as combination therapy or utilization of new antimicrobial agents might help to combat such drug-resistant organisms.

Distribution of resistance genes encoding ESBLs in Enterobacteriaceae isolated from biological samples in health centers in Ouagadougou, Burkina Faso

Objective

Resistance to antibiotics most especially third generation cephalosporins has assumed a worrisome dimension globally. Genes conferring these resistance which are mediated by enzymes known as extended spectrum beta-lactamases (ESBLs) are now wide spread among several Enterobacteriaceae species. However there is paucity of data regarding the distribution of these genes in Burkina Faso. Hence this prospective study aims to determine the prevalence and distribution of ESBL encoding genes in ESBL producing Enterobacteriaceae strains isolated from clinical samples of patients attending the three major hospitals in Ouagadougou Burkina Faso.

Results

ESBL-encoding genes were assayed in 187 ESBL producing Enterobacteriaceae strains. Among these isolates, the prevalence of ESBL-producing strains with blaTEM, blaSHV and blaCTX-M genes were 26.2% (49/187), 5.9% (11/187) and 40.1% (75/187) respectively. The association of ESBL encoding genes with health centers was statistically significant (p = 0.0209). Approximately 39.6% of E. coli harbored CTX-M and Klebsiella spp. 5.9%. This study demonstrates the dissemination of TEM, SHV and CTX-M genes in ESBL producing Enterobacteriaceae strains in Ouagadougou. Continuous spread of these bacteria poses great public health risk, thus increased surveillance and regulation of antibiotics use is imperative in Burkina Faso.

Synthesis, Spectroscopic Characterization, and In Vitro Antibacterial Evaluation of Novel Functionalized Sulfamidocarbonyloxyphosphonates

Several new sulfamidocarbonyloxyphosphonates were prepared in two steps, namely carbamoylation and sulfamoylation, by using chlorosulfonyl isocyanate (CSI), α-hydroxyphosphonates, and various amino derivatives and related (primary or secondary amines, β-amino esters, and oxazolidin-2-ones). All structures were confirmed by ¹H, ¹³C, and ³¹P NMR spectroscopy, IR spectroscopy, and mass spectroscopy, as well as elemental analysis. Eight compounds were evaluated for their in vitro antibacterial activity against four reference bacteria including Gram-positive Staphylococcus aureus (ATCC 25923), and Gram-negative Escherichia coli (ATCC 25922), Klebsiella pneumonia (ATCC 700603), Pseudomonas aeruginosa (ATCC 27853), in addition to three clinical strains of each studied bacterial species. Compounds 1a⁻7a and 1b showed significant antibacterial activity compared to sulfamethoxazole/trimethoprim, the reference drug used in this study.

The Threat and Response to Infectious Diseases (Revised)

The threat from microorganisms is complex, and the approaches for reducing the challenges the world is facing are also multifaceted, but a combination approach including several simple steps can make a difference and reduce morbidity and mortality and the economic cost of fighting infectious diseases. This paper discusses the continually evolving infectious disease landscape, contributing factors in the rise of the threat, reasons for optimism, and the policies, technologies, actions, and institutions that might be harnessed to further reduce the dangers introduced by pathogens. It builds upon and updates the work of other authors that have recognized the dangers of emerging and re-emerging pathogens and have explored and documented potential solutions.

Susceptibility of sodA- and sodB-deficient Escherichia coli mutant towards antimicrobial photodynamic inactivation via the type I-mechanism of action

Photodynamic antimicrobial chemotherapy (PACT) is a multi-target method to inactivate pathogenic microorganisms by exciting a photosensitizer (PS) with visible light of appropriate wavelength in the presence of molecular oxygen (³O₂). There are two major pathways by which reactive oxygen species (ROS) are produced. In type I (T_I)-reactions, radicals such as superoxide (O₂˙^-) and hydroxyl radicals (˙OH) are generated by electron transfer. In type II (T_II)-reactions, highly reactive singlet oxygen (¹O₂) is produced by direct energy transfer. This study investigated the efficiency of PACT in Gram-negative Escherichia coli wild type (EC WT) and the mutant Escherichia coli PN134 (EC PN134) which is not able to produce SOD A and SOD B, by means of two different photosensitizers (PS) from different chemical classes with different ¹O₂ quantum yields: methylene blue (MB) and 5,10,15,20-tetrakis(1-methyl-4-pyridinio)porphyrin tetra(p-toluenesulfonate) (TMPyP). Mutants, which lack antioxidant enzymes, were particularly susceptible towards T_I-PACT. In the case of PACT with MB, quenching agents such as superoxide dismutase (SOD) and catalase (CAT) were sufficient for protecting both the wild type and the mutant, whereas they were not in PACT with TMPyP. The genetic levels of sodA and sodB were examined after photodynamic treatment regarding their potential resistance. This study showed that - under the photodynamic conditions presented in this study - expression of sodA and sodB was not directly influenced by PACT-generated oxidative stress, although SOD enzymes are part of the major defense machinery against oxidative stress and were thus expected to be upregulated. Overall the susceptibility of EC PN134 and EC WT differed towards photodynamic inactivation via T_I-mechanism of action. Thus, already existing defense mechanisms against ROS in bacteria might influence the susceptibility against T_I-PACT, while this was not the case using T_II-photosensitizers.

Comparison of Septic Shock Due to Multidrug-Resistant Acinetobacter baumannii or Klebsiella pneumoniae Carbapenemase-Producing K. pneumoniae in Intensive Care Unit Patients

A significant cause of mortality in the intensive care unit (ICU) is multidrug-resistant (MDR) Gram-negative bacteria, such as MDR Acinetobacter baumannii (MDR-AB) and Klebsiella pneumoniae carbapenemase-producing K. pneumoniae (KPC-Kp). The aim of the present study was to compare the clinical features, therapy, and outcome of patients who developed septic shock due to either MDR-AB or KPC-Kp. We retrospectively analyzed patients admitted to the ICU of a teaching hospital from November 2010 to December 2015 who developed septic shock due to MDR-AB or KPC-Kp infection. Data from 220 patients were analyzed: 128 patients (58.2%) were diagnosed with septic shock due to KPC-Kp, and 92 patients (41.8%) were diagnosed with septic shock due to MDR-AB. The 30-day mortality rate was significantly higher for the MDR-AB group than the KPC-Kp group (84.8% versus 44.5%, respectively; P < 0.001). Steroid exposure and pneumonia were associated with MDR-AB infection, whereas hospitalization in the previous 90 days, primary bacteremia, and KPC-Kp colonization were associated with KPC-Kp infection. For patients with KPC-Kp infections, the use of ≥2 in vitro-active antibiotics as empirical or definitive therapy was associated with higher 30-day survival, while isolation of colistin-resistant strains was linked to mortality. Patients with MDR-AB infections, age >60 years, and a simplified acute physiology score II (SAPS II) of >45 points were associated with increased mortality rates. We concluded that septic shock due to MDR-AB infection is associated with very high mortality rates compared to those with septic shock due to KPC-Kp. Analysis of the clinical features of these critically ill patients might help physicians in choosing appropriate empirical antimicrobial therapy.

Infection therapy: the problem of drug resistance - and possible solutions

The rising antibiotic resistance in major bacterial pathogens together with the breakdown of the antibiotic discovery platform creates a critical situation for infection therapy. Recent developments reviving new antibiotic discovery from defining chemical rules for membrane-passing compounds to isolation chips for soil bacteria and exploring the human microbiome for antibiotic-producing bacteria are discussed. The potential of bacteriocins, tailocins, phage lysins, phages, probiotics and commensal blends as alternatives to antibiotics is evaluated.

The analysis of tetracyclines, quinolones, macrolides, lincosamides, pleuromutilins, and sulfonamides in chicken feathers using UHPLC-MS/MS in order to monitor antibiotic use in the poultry sector

In The Netherlands, all antibiotic treatments should be registered at the farm and in a central database. To enforce correct antibiotic use and registration, and to enforce prudent use of antibiotics, there is a need for methods that are able to detect antibiotic treatments. Ideally, such a method is able to detect antibiotic applications during the entire lifespan of an animal, including treatments administered during the first days of the animals' lives. Monitoring tissue, as is common practice, only provides a limited window of opportunity, as residue levels in tissue soon drop below measurable quantities. The analysis of feathers proves to be a promising tool in this respect. Furthermore, a qualitative confirmatory method was developed for the analyses of six major groups of antibiotics in ground chicken feathers, aiming for a detection limit as low as reasonably possible. The method was validated according to Commission Decision 2002/657/EC. All compounds comply with the criteria and, as a matter of fact, 58% of the compounds could also be quantified according to regulations. Additionally, we demonstrated that a less laborious method, in which whole feathers were analyzed, proved successful in the detection of applied antibiotics. Most compounds could be detected at levels of 2 μg kg-1 or below with the exception of sulfachloropyridazine, tylosin, and tylvalosin. This demonstrates the effectiveness of feather analysis to detect antibiotic use to allow effective enforcement of antibiotic use and prevent the illegal, off-label, and nonregistered use of antibiotics.

Molecular Characterization of ESBL-Producing Escherichia Coli Isolated from Healthy Cattle and Sheep

The present study aims to characterize ESBL-producing Escherichia coli isolated from healthy cattle and sheep in the Burdur province of Turkey. Fecal samples from a total of 200 cattle and 200 sheep were tested and ESBL-producing E. coli was isolated from 31 (15.5%) cattle and three (1.5%) sheep samples using the Clinical and Laboratory Standards Institute’s combined disk method. Among the ESBL gene classes detected by PCR, blaCTX-M was the most frequent type, followed by the blaTEM and blaSHV families. ESBL-producing E. coli isolates showed co-resistance to multiple classes of antibiotics including aminoglycosides, phenicols, quinolones, folate pathway inhibitors and tetracyclines. The resistance rates were higher in the cattle isolates than in the sheep isolates. Phylogenetic grouping of the E. coli isolates indicated group A (particularly A1) was the predominant phylogenetic group (19/34, 55.9%), followed by groups B1 (9/34, 26.5%) and D (6/34, 17.6%); none of the isolates belonged to group B2. The study shows that ESBL-producing E. coli isolates exist in the intestinal flora of healthy cattle and sheep in the Burdur province of Turkey. This is the first report showing the emergence of CTX-M type ESBL-producing E. coli in sheep farms in Turkey

Extensively drug-resistant Acinetobacter baumannii outbreak cross-transmitted in an intensive care unit and respiratory intensive care unit

BACKGROUND

Extensively drug-resistant Acinetobacter baumannii (XDRAB) is a great threat in intensive care units (ICUs). The aim of this study was to describe an XDRAB outbreak which was cross-transmitted in the ICU and respiratory intensive care unit (RICU) in a tertiary care hospital from January-March 2013.

METHODS

Patient and environmental surveillances were performed. Isolates were tested for antimicrobial susceptibility. Genotypes were analyzed by multilocus sequence typing (MLST). A series of enhanced strategies were implemented to control the outbreak.

RESULTS

A total of 11 patients were infected by XDRAB strains during this outbreak. Three patients in the ICU were found positive for XDRAB at the onset of the outbreak. Thereafter, infections were detected in 6 patients in the RICU, followed by reappearance of this strain in the ICU in 2 patients. All A baumannii strains isolated from patients and the environment were extensively drug resistant. MLST revealed them as ST368. After 3 rounds of environmental screening and cleaning, the laminar flow system connecting the ICU and RICU was found as the source of transmission. Successful control of this outbreak was achieved through multifaceted intervention measures.

CONCLUSIONS

This study suggested the importance of thorough surveillance and disinfection of the environment, including concealed devices, in preventing the transmission of an outbreak.

Biofilm Formation and Motility Depend on the Nature of the Acinetobacter baumannii Clinical Isolates

Acinetobacter baumannii is a nosocomial pathogen involved in various infections ranging from minor soft-tissue infections to more severe infections such as ventilator-associated pneumonia and bacteremia. The severity and the type of infections depend on the genetic and phenotypic variations of the strains. In this study, we compared the extent of biofilm formation and motility displayed by 60 multidrug-resistant A. baumannii clinical strains isolated from blood and sputum samples from patients from Southern India. Our results showed that isolates from the sputum samples formed significantly more robust biofilm compared to the blood isolates. On the other hand, we observed that the blood isolates were more motile than the sputum isolates. To the best of our knowledge, this is the first study that systematically evaluated the correlation between these two phenotypic traits and the nature of the isolates.

Acinetobacter baumannii Infection and IL-17 Mediated Immunity

Acinetobacter baumannii is a significant cause of severe hospital-acquired infections with a recent rise in multidrug-resistant infections involving traumatic wounds of military personnel. The interleukin-17 (IL-17) pathway is essential for neutrophil recruitment in response to a variety of pathogens, while the control of A. baumannii infection is known to be dependent on neutrophils. This suggests that IL-17 may play an important role in A. baumannii infection; however, this has yet to be studied. Here, we summarize the recent advances in understanding the host-pathogen interaction of A. baumannii and propose a potential role of the IL-17 pathway in generating a protective immune response.

The impact of cationic substituents in phenalen-1-one photosensitizers on antimicrobial photodynamic efficacy

SAGUA with its guanidinium moiety reaching an efficacy of ≥6log₁₀ steps of bacteria killing at 10 μM after irradiation with blue light (20 mW cm⁻²) for 60 s (1.2 J cm⁻²) without exhibiting dark toxicity.

A computational model to monitor and predict trends in bacterial resistance

Current concern over the emergence of multidrug-resistant superbugs has renewed interest in approaches that can monitor existing trends in bacterial resistance and make predictions of future trends. Recent advances in bacterial surveillance and the development of online repositories of susceptibility tests across wide geographical areas provide an important new resource, yet there are only limited computational tools for its exploitation. Here we propose a hybrid computational model called BARDmaps for automated analysis of antibacterial susceptibility tests from surveillance records and for performing future predictions. BARDmaps was designed to include a structural computational model that can detect patterns among bacterial resistance changes as well as a behavioural computational model that can use the detected patterns to predict future changes in bacterial resistance. Data from the European Antimicrobial Resistance Surveillance Network (EARS-Net) were used to validate and apply the model. BARDmaps was compared with standard curve-fitting approaches used in epidemiological research. Here we show that BARDmaps can reliably predict future trends in bacterial resistance across Europe. BARDmaps performed better than other curve-fitting approaches for predicting future resistance levels. In addition, BARDmaps was also able to detect abrupt changes in bacterial resistance in response to outbreaks and interventions as well as to compare bacterial behaviour across countries and drugs. In conclusion, BARDmaps is a reliable tool to automatically predict and analyse changes in bacterial resistance across Europe. We anticipate that BARDmaps will become an invaluable tool both for clinical providers and governmental agencies to help combat the threat posed by antibiotic-resistant bacteria.

Antivirals against enteroviruses: a critical review from a public-health perspective

The enteroviruses (EVs) of the Picornaviridae family are the most common viral pathogens known. Most EV infections are mild and self-limiting but manifestations can be severe in children and immunodeficient individuals. Antiviral development is actively pursued to benefit these high-risk patients and, given the alarming problem of antimicrobial drug resistance, antiviral drug resistance is a public-health concern. Picornavirus antivirals can be used off-label or as part of outbreak control measures. They may be used in the final stages of poliovirus eradication and to mitigate EV-A71 outbreaks. We review the potential emergence of drug-resistant strains and their impact on EV transmission and endemic circulation. We include non-picornavirus antivirals that inhibit EV replication, for example, ribavirin, a treatment for infection with HCV, and amantadine, a treatment for influenza A. They may have spurred resistance emergence in HCV or influenza A patients who are unknowingly coinfected with EV. The public-health challenge is always to find a balance between individual benefit and the long-term health of the larger population.

A general ANN-based multitasking model for the discovery of potent and safer antibacterial agents

Bacteria have been one of the world's most dangerous and deadliest pathogens for mankind, nowadays giving rise to significant public health concerns. Given the prevalence of these microbial pathogens and their increasing resistance to existing antibiotics, there is a pressing need for new antibacterial drugs. However, development of a successful drug is a complex, costly, and time-consuming process. Quantitative Structure-Activity Relationships (QSAR)-based approaches are valuable tools for shortening the time of lead compound identification but also for focusing and limiting time-costly synthetic activities and in vitro/vivo evaluations. QSAR-based approaches, supported by powerful statistical techniques such as artificial neural networks (ANNs), have evolved to the point of integrating dissimilar types of chemical and biological data. This chapter reports an overview of the current research and potential applications of QSAR modeling tools toward the rational design of more efficient antibacterial agents. Particular emphasis is given to the setup of multitasking models along with ANNs aimed at jointly predicting different antibacterial activities and safety profiles of drugs/chemicals under diverse experimental conditions.

Antimicrobial photodynamic therapy for inactivation of biofilms formed by oral key pathogens

With increasing numbers of antibiotic-resistant pathogens all over the world there is a pressing need for strategies that are capable of inactivating biofilm-state pathogens with less potential of developing resistances in pathogens. Antimicrobial strategies of that kind are especially needed in dentistry in order to avoid the usage of antibiotics for treatment of periodontal, endodontic or mucosal topical infections caused by bacterial or yeast biofilms. One possible option could be the antimicrobial photodynamic therapy (aPDT), whereby the lethal effect of aPDT is based on the principle that visible light activates a photosensitizer (PS), leading to the formation of reactive oxygen species, e.g., singlet oxygen, which induce phototoxicity immediately during illumination. Many compounds have been described as potential PS for aPDT against bacterial and yeast biofilms so far, but conflicting results have been reported. Therefore, the aim of the present review is to outline the actual state of the art regarding the potential of aPDT for inactivation of biofilms formed in vitro with a main focus on those formed by oral key pathogens and structured regarding the distinct types of PS.

Bactericidal activities of GM flax seedcake extract on pathogenic bacteria clinical strains

BACKGROUND

The antibiotic resistance of pathogenic microorganisms is a worldwide problem. Each year several million people across the world acquire infections with bacteria that are antibiotic-resistant, which is costly in terms of human health. New antibiotics are extremely needed to overcome the current resistance problem.

RESULTS

Transgenic flax plants overproducing compounds from phenylpropanoid pathway accumulate phenolic derivatives of potential antioxidative, and thus, antimicrobial activity. Alkali hydrolyzed seedcake extract containing coumaric acid, ferulic acid, caffeic acid, and lignan in high quantities was used as an assayed against pathogenic bacteria (commonly used model organisms and clinical strains). It was shown that the extract components had antibacterial activity, which might be useful as a prophylactic against bacterial infection. Bacteria topoisomerase II (gyrase) inhibition and genomic DNA disintegration are suggested to be the main reason for rendering antibacterial action.

CONCLUSIONS

The data obtained strongly suggest that the seedcake extract preparation is a suitable candidate for antimicrobial action with a broad spectrum and partial selectivity. Such preparation can be applied in cases where there is a risk of multibacterial infection and excellent answer on global increase in multidrug resistance in pathogenic bacteria.

A peptide of heparin cofactor II inhibits endotoxin-mediated shock and invasive Pseudomonas aeruginosa infection

Sepsis and septic shock remain important medical problems with high mortality rates. Today's treatment is based mainly on using antibiotics to target the bacteria, without addressing the systemic inflammatory response, which is a major contributor to mortality in sepsis. Therefore, novel treatment options are urgently needed to counteract these complex sepsis pathologies. Heparin cofactor II (HCII) has recently been shown to be protective against Gram-negative infections. The antimicrobial effects were mapped to helices A and D of the molecule. Here we show that KYE28, a 28 amino acid long peptide representing helix D of HCII, is antimicrobial against the Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa, the Gram-positive Bacillus subtilis and Staphylococcus aureus, as well as the fungus Candida albicans. Moreover, KYE28 binds to LPS and thereby reduces LPS-induced pro-inflammatory responses by decreasing NF-κB/AP-1 activation in vitro. In mouse models of LPS-induced shock, KYE28 significantly enhanced survival by dampening the pro-inflammatory cytokine response. Finally, in an invasive Pseudomonas infection model, the peptide inhibited bacterial growth and reduced the pro-inflammatory response, which lead to a significant reduction of mortality. In summary, the peptide KYE28, by simultaneously targeting bacteria and LPS-induced pro-inflammatory responses represents a novel therapeutic candidate for invasive infections.

Infections Caused by Acinetobacter baumannii in Recipients of Hematopoietic Stem Cell Transplantation

Acinetobacter baumannii (A. baumannii) is a Gram-negative, strictly aerobic, non-fermentative coccobacillus, which is widely distributed in nature. Recently, it has emerged as a major cause of health care-associated infections (HCAIs) in addition to its capacity to cause community-acquired infections. Risk factors for A. baumannii infections and bacteremia in recipients of hematopoietic stem cell transplantation include: severe underlying illness such as hematological malignancy, prolonged use of broad-spectrum antibiotics, invasive instrumentation such as central venous catheters or endotracheal intubation, colonization of respiratory, gastrointestinal, or urinary tracts in addition to severe immunosuppression caused by using corticosteroids for treating graft versus host disease. The organism causes a wide spectrum of clinical manifestations, but serious complications such as bacteremia, septic shock, ventilator-associated pneumonia, extensive soft tissue necrosis, and rapidly progressive systemic infections that ultimately lead to multi-organ failure and death are prone to occur in severely immunocompromised hosts. The organism is usually resistant to many antimicrobials including penicillins, cephalosporins, trimethoprim-sulfamethoxazole, almost all fluoroquinolones, and most of the aminoglycosides. The recently increasing resistance to carbapenems, colistin, and polymyxins is alarming. Additionally, there are geographic variations in the resistance patterns and several globally and regionally resistant strains have already been described. Successful management of A. baumannii infections depends upon appropriate utilization of antibiotics and strict application of preventive and infection control measures. In uncomplicated infections, the use of a single active beta-lactam may be justified, while definitive treatment of complicated infections in critically ill individuals may require drug combinations such as colistin and rifampicin or colistin and carbapenem. Mortality rates in patients having bacteremia or septic shock may reach 70%. Good prognosis is associated with presence of local infection, absence of multidrug resistant strain, and presence of uncomplicated infection while poor outcome is associated with severe underlying medical illness, bacteremia, septic shock, multi-organ failure, HCAIs, admission to intensive care facilities for higher levels of care, and culture of certain aggressive genotypes of A. baumannii.

Blue light kills Aggregatibacter actinomycetemcomitans due to its endogenous photosensitizers

OBJECTIVES

The aim of this study was to demonstrate that the periodontal pathogen Aggregatibacter actinomycetemcomitans (AA) can be killed by irradiation with blue light derived from a LED light-curing unit due to its endogenous photosensitizers.

MATERIALS AND METHODS

Planktonic cultures of AA and Escherichia coli were irradiated with blue light from a bluephase® C8 light-curing unit with an emission peak at 460 nm, which is usually applied for polymerization of dental resins. A CFU-assay was performed for the analysis of viable bacteria after treatment. Moreover, bacterial cells were lysed and the lysed AA and E. coli were investigated for generation of singlet oxygen. Spectroscopic measurements of lysed AA and E. coli were performed and analyzed for characteristic absorption and emission peaks.

RESULTS

A light dose of 150 J/cm(2) induced a reduction of ≥5 log10 steps of viable AA, whereas no effect of blue light was found against E. coli. Spectrally resolved measurements of singlet oxygen luminescence showed clearly that a singlet oxygen signal is generated from lysed AA upon excitation at 460 nm. Spectroscopic measurements of lysed AA exhibited characteristic absorption and emission peaks similar to those of known porphyrins and flavins.

CONCLUSIONS

AA can be inactivated by irradiation with blue light only, without application of an exogenous photosensitizer.

CLINICAL RELEVANCE

These results encourage further studies on the potential use of these blue light-mediated auto-photosensitization processes in the treatment of periodontitis for the successful inactivation of Aggregatibacter actinomycetemcomitans.

Photodynamic biofilm inactivation by SAPYR--an exclusive singlet oxygen photosensitizer

Prevention and control of biofilm-growing microorganisms are serious problems in public health due to increasing resistances of some pathogens against antimicrobial drugs and the potential of these microorganisms to cause severe infections in patients. Therefore, alternative approaches that are capable of killing pathogens are needed to supplement standard treatment modalities. One alternative is the photodynamic inactivation of bacteria (PIB). The lethal effect of PIB is based on the principle that visible light activates a photosensitizer, leading to the formation of reactive oxygen species, e.g., singlet oxygen, which induces phototoxicity immediately during illumination. SAPYR is a new generation of photosensitizers. Based on a 7-perinaphthenone structure, it shows a singlet oxygen quantum yield ΦΔ of 99% and is water soluble and photostable. Moreover, it contains a positive charge for good adherence to cell walls of pathogens. In this study, the PIB properties of SAPYR were investigated against monospecies and polyspecies biofilms formed in vitro by oral key pathogens. SAPYR showed a dual mechanism of action against biofilms: (I) it disrupts the structure of the biofilm even without illumination; (II) when irradiated, it inactivates bacteria in a polymicrobial biofilm after one single treatment with an efficacy of ≥ 99.99%. These results encourage further investigation on the potential of PIB using SAPYR for the treatment of localized infectious diseases.

Endophthalmitis following cataract surgery: the role of prophylactic postoperative chloramphenicol eye drops

PURPOSE

The main aim of the study was to assess whether omitting prophylactic postoperative topical antibiotics (chloramphenicol) influenced the risk of developing endophthalmitis after cataract surgery.

METHODS

We conducted a retrospective study including all patients who had cataract surgery at our outpatient cataract unit between 2004 and 2011. Postoperative topical antibiotics (chloramphenicol) were omitted from 2007 onwards, as was the first postoperative day review. Patients with a diagnosis of endophthalmitis after cataract surgery were extracted, and the rate of postoperative endophthalmitis (PE) before and after changing these routines was compared. The diagnosis of PE was defined as severe intraocular inflammation requiring prompt vitreous sampling for culture.

RESULTS

Seven thousand one hundred and twenty-three and 8131 cataract surgeries were performed in the following periods: January 2004 through December 2006 (period 1) and January 2007 through December 2010 (period 2), respectively. Five cases of PE were identified in period 1 (0.070%) and four patients in period 2 (0.049%). The median time between cataract surgery and onset of symptoms was 6 days in period 1 and 4.5 days in period 2. Median time for intervention was 7 and 5 days postsurgery, respectively.

CONCLUSION

We found no difference in the frequency of PE following cataract surgery when changing the postoperative topical medication from a mixture of corticosteroids and antibiotics to only corticosteroids.